1. Field of the Invention
This invention pertains to the field of battery cells, and in particular, metal-gas batteries, such as nickel hydrogen batteries.
2. Description of the Prior Art
A prior art search uncovered the following U.S. patent references:
U.S. Pat. No. 4,115,630 accomplishes one of the goals of the present invention, i.e., the equal aging of electrode modules by means of equalization of resistance among internal paths traversing all modules; however, this patent does not suggest how this goal can be accomplished with the further goal of locating both terminals at the same end of the cell. In fact, integral to the design of the U.S. Pat. No. 4,115,630, patent is the placement of each terminal along the cells's cylindrical axis, thereby precluding placement of both terminals at the same end.
U.S. Pat. No. 3,956,015 places both terminals on one side of the cell, although the terminals are perpendicular to the wall of the cell, unlike in the present invention. The U.S. Pat. No. 3,956,015 patent attempts to equalize the resistance within the cell for all module paths by means of utilizing individual leads from the terminals to each electrocde. The path resistances are not exactly equal, however, because there are always minor variations in sizing and connecting the leads. Furthermore, since the leads have to be insulated from each other, the resulting design is cumbersome, heavy, and unsuitable for spacecraft applications.
U.S. Pat. Nos. 3,899,351; 4,004,067; 4,004,068; 4,098,962; 4,127,703; 4,128,703; and 4,159,367 show battery cells with positive and negative terminals situated on the same end of the cell. However, none of the patents teaches the use of resistance balancing among module paths so as to prolong the life of the battery as in the present invention.
U.S. Pat. No. 3,846,174 shows resistance balancing within a module, but not from module to module.